October 27, 2016 Process Monitoring for Biological and Chemical Nutrient Removal OWEA 2016 PLANT OPERATIONS & LABORATORY WORKSHOP
Agenda Why Consider Nutrient Removal? Nitrogen Monitoring & Removal Phosphorus Monitoring & Removal 2
Why Nutrient Removal? Required by Discharge Permit Improve Water Quality (avoid future limit) Increase Revenue (water quality trading) Stabilize Process Save Energy Recover Nutrients (P) 3
kwh / MG Energy Intensity Benchmarking 2,500 2,000 1,934 1,853 1,955 1,500 1,000 1,412 973 1,249 1,118 1,202 Typical Best Practice 500 4 0 Basic Secondary Nitrification BNR ENR Joint WEF/WERF Webcast: Net Zero Energy Solutions for Water Resource Recovery Facilities Wednesday, October 29th, 2014
P Removal and Recovery Detergent Human Industry Plants WWTP P Recovery Fertilization Mining Weathering Agriculture Runoff Discharge X Phosphate rock Rivers & lakes Tectonic uplift Sedimentation Sediments Cornel et al (2009)
Nitrogen Monitoring 6
Cabinet Analyzer 7
Ion Selective Electrode 8
Specifications IQSN Nutrient ISEs Specification Ammonium Nitrate Potassium Chloride Measuring Range mg /L (as N)* Resolution mg /L (as N)* Response Time min. 0.1 to 100 / 1.0 to 2,000 0.1 to 100 1.0 to 1,000 0.1 to 100 1.0 to 1,000 0.1 to 100 1.0 to 1,000 0.1 / 1.0 0.1 / 1.0 0.1 / 1.0 (as K) 0.1 / 1.0 (as Cl) < 3 9
Response Time 10 Automation of Wastewater Treatment Facilities, 3 rd Edition, WEF MOP-21, WEF Press, Alexandria, VA, 2007.
Optical 11
ISE vs. Optical Nitrate Monitoring - Optical ISE Measuring range, mg/l as N 60 / 150 0 to 1,000 Resolution 0.01 0.1 Pressure resistance, bar 1 0.2 Power Consumption, W Up to 8 0.2 Response time (t 90 ), min. Programmable < 3 Temperature measurement No Yes Additional Parameters / probe COD/BOD/TOC, NO 2, TSS NH 4, K, Cl Warranty (probe), yrs 2 2 Warranty (electrodes), yrs NA 1
Nitrogen Removal 13
The Microbiological Nitrogen Cycle OHO NO 2 - NOB AOB
Nitrogen Removal Configuration 3-4 Q NO 3 -N IMLR or NRCY WW Anoxic NH 3 BOD Oxic NO 3 -N NO 3 -N Clarifier NO 3 NO 3 N 2 NH 3 NO 3 RAS NO 3 -N 15
Delaware County RSD A N O A N O H Anoxic Oxic
Denitrification Process Control Chart 17
4-Stage Bardenpho 3-4 Q NO 3 -N Methanol or Glycerin Anoxic Internal MLSS Recycle Aerobic Anoxic Aerobic Q BOD NH3-N Aerobic 3-5 mg/l TN RAS NO 3 -N Distance
Denitrification Monitoring WSSC Seneca 5 x NitraVis 701 TS (1 in each train) w/ supplemental air cleaning (MIQ/CHV) Goals: Effluent < 4.0 mg N/L (permit) Effluent < 3.0 mg N/L ($300k credit) Minimize Methanol N 19
Step Feed Denitrification NYC DEP 63 x NitraVis 701 IQ Goals: Target Effluent TN = 7 to 8 mg N/L Monitoring of oxic zone nitrate Feed forward Feedback control of carbon addition (NIC-NOT) 20
Phosphorus Monitoring 21
Orthophosphate (PO 4 3- ) Environmental P is Phosphate Soluble P is orthophosphate Colorimetry is the primary method of detection
Phosphorus Characterization TP OP
Orthophosphate Analyzer Low reagent consumption Suitable for outdoors Automatic calibration Integrated permeate pump Filter module 24
Technical Specifications Range (mg P / L) Accuracy Lo: 0.05 to 15 mg P / L 2% or 0.05 Hi: 1 to 50 mg P / L mg P / L Response time (min.) Detection limit (mg P / L) Reagent Replenishment < 5 0.05 mg P / L 2.5 L / 4 mths. 25
Phosphorus Removal 26
How is P Removed? 1. Biological 2. Chemical P Basic concept: P soluble P Particulate
Chemical P Removal Fe/ Al Fe / Al Fe / Al Fe / Al Pre-precipitation Simultaneous precipitation Post precipitation P P
Chemical Dosing Control Manual Flow-proportioned (Feed Forward) Feedback with analyzer 29
Feedback Control Example Fe P700 0.61 0.65 0.05 0.50% 900 HOLD P 0.10
Chemical Dosing System Operation 31
Phosphorus Accumulating Organism (PAO)
A / O Process VFA RAS Concentrations in Bioreactor PAO P Anaerobic Ortho-P PAO P Aerobic 3 x Infl. Ortho-P P-Rich WAS PHB Storage BOD BOD Oxidized Net P Removal Location in Bioreactor
Flow Sheet GC Sugar Creek Effluent Ultraviolet Disinfection
Process Control - ORP
Summary There are many compelling reasons to consider nutrient removal Multiple reliable online monitoring technologies are available for nitrogen monitoring. Nitrogen removal is achieved through modification of the well-known activated sludge process to exploit the microbiological nitrogen cycle Online phosphorus monitoring requires a cabinet analyzer but the technology is improving to reduce maintenance and cost Phosphorus removal can be achieved chemically or through enrichment of phosphate accumulating organisms (PAO) 36
Questions? 37